Here’s their manifesto and action-plan, copied straight from the website at www.bristolstreettrees.org

Bristol Street Trees – The Future
If Bristol is to be the green capital we must halt the felling and plant large trees
Across Britain, street trees are being removed at an alarming rate. In Bristol, many are never replaced and when replanting does occur, it is often with smaller trees that will not achieve the stature of those that were removed. In an effort to avoid compensation and reduce maintenance costs the majestic London planes and limes that define our city are being replaced with gardenesque flowering cherries, rowans and birches. Large trees bring huge benefits for the community: beyond the aesthetic, they absorb particulates and noise, they provide protection against extremes of hot and cold, they are an ecological resource and they absorb water run off and reduce flooding. Their health benefits are significant, and their presence has been shown to reduce anti-social behaviour and crime.
Most large city trees on private land are protected by law: street trees are not. The character of our city is changing through death by a thousand cuts. Often the trees that are most needed, such as on busy thoroughfares, have few champions. Only those who want to see trees removed have a stake in the debate. Unproven compensation claims for subsidence result in the removal of trees, when the real problem is that Victorian houses were built without adequate foundations. Bristol needs to force a change in the compensation culture that is responsible for the loss of so many street trees. This needs to be done, not only through the legal process but also by making it socially unacceptable to press for the removal of trees. Those who live in an area with trees should recognise the benefits and likewise accept the risks or move out. The city needs to be robust in the defence of trees.
The last time that large numbers of street trees were planted was in the early 1970s, when more than 2,000 were planted. Before that the Victorians, with a vision for the future, planted many of the avenues and landmark trees that grace our city. A third period of planting is now needed. This should be bold and dynamic and provide the city with landmark trees and avenues for the future.
Street trees are urban assets not financial liabilities. We need a process of public consultation before the removal of any street tree and in street tree planting; in the choice of species, the location of new trees, and finding funding for new or replacement trees. The city council needs to develop a street tree strategy through a proper process for public consultation. We need a simple procedure for planting street trees and the various departments to work together. Once this mechanism is in place, funds can be raised as they were in the 1970s. We can then replace missing trees and take advantage of new opportunities. Every new highways project should have a street tree component. For every showcase bus route we need a showcase tree route.
A grand gesture such as a dramatic avenue should kick start a new golden age of planting.
Bristol Street Trees: Proposal for a Way Forwards.
1. Develop a street tree strategy for Bristol for 2008-2013 following a proper period of public consultation.
2. Publish information on the council web site. Start a process of engaging and consulting with the public (as required under EC Law and in common with the activities of many other parts of BCC) by providing information on Bristol’s street trees on the council web site. Such information should include the most frequently asked questions (FAQ) and should also seek to educate the public regarding the value of street trees. The web site should contain information on how to get a street tree planted in a new location, or a felled tree replaced in an existing location. In addition there should be ongoing information regarding the street trees and species that are being planted and those that are being felled.
3. Adopt a proper process of consultation before street trees are removed (also required under EC law). This could be similar to the planning (or TPO) process and would include a notice inviting comment on the tree in question and full information regarding the origin of the request for the tree to be removed. This would bring into the open the desires of insurance companies and residents who wish to see trees removed. It would also bring people who wish to see trees retained into the debate, as stakeholders in their local environment.
4. Where necessary, impose TPOs on council or highway trees, providing them with legal protection from opportunist compensation claims. Fight any claims if or as they arise.
5. Any Bristol City Council property with landmark trees must only be sold with a covenant protecting them. The BCC property and finance department must develop a strategy for saving important trees.
6. Develop a mechanism for ensuring that there is proper communication and consultation with the public. This would be easier once information is included on the web site. Set up a regular cycle of communication and meetings with the occupants of each area of Bristol. Through this process, harness the great interest and take advantage of the professional expertise of some members of the public. This kind of process is conducted in many other arenas.
7. Instigate an urban design framework within the relevant city council departments so that for each new council development (such as pavement build-outs and showcase bus routes) there is consideration of new planting opportunities. The council must acknowledge that whilst an aboriculturalist is able to determine the health and status of an individual tree an urban design professional is required to address the wider, long term picture for the city.
8. Once again start planting street trees that will become large in order to halt the insidious change to our city which still benefits from large trees. Once a mechanism has been found for planting street trees , we do not see funding as a problem. The public can help with fund-raising. Locations for new avenues need to be identified and missing trees in existing avenues replaced